This invention relates to laser indicator devices used in sporting-type games. More particularly, this invention relates to laser indicator devices used in baseball games.
In the game of baseball, a pitcher will throw a "strike" if he pitches a baseball through a region called a "Strike Zone". According to official baseball rules the strike zone of a batter is that area over home plate the upper limit of which is a horizontal line at the midpoint between the top of the batter's shoulders and the top of his uniform pants, and the lower level is at the hollow beneath the batter's knee cap. Furthermore, the Strike Zone is determined from the batter's stance as the batter is prepared to swing at a pitched ball. A pitched ball which passes through the Strike Zone is called a "strike". Any pitch that does not pass through the Strike Zone, and is not swung at by the batter is called a "ball".
Because a pitched baseball passes through the Strike Zone only for a fraction of a second, it is quite probable that a home plate umpire calling balls and strikes will make mistakes. For example, a baseball which passes just slightly outside of the Strike Zone might be accidentally called a strike. Accordingly, it would be advantageous to have a device which could help the home plate umpire in calling balls and strikes.
Several attempts have been made to devise strike zone indicators. For example, U.S. Pat. No. 5,676,607 issued Oct. 14, 1997 to Stumpf teaches a laser beam Strike Zone indicator. The device of the patent includes a home plate having a plurality of adjustable light beam sources which are directed upwardly from the home plate to define a vertical rectangle at the front of the home plate which represents the Strike Zone for the height of a predetermined batter.
One disadvantage of the device of this patent is that the lasers are only meant to outline portions of the edges of the Strike Zone. According to the disclosure of the Stumpf patent, it is quite possible that a ball pitched through the Strike Zone would not intersect a laser beam at all. It is noted that a laser beam passing through air is generally difficult to see. Therefore it is possible that no visual indication would be provided to a home umpire at all.
A number of devices have also been suggested for determining pitching accuracy in practice-type settings. Such devices often include light transmitters and light receivers, and indicate a strike when light is blocked by passage of a ball, see for example U.S. Pat. No. 5,230,505 issued Jul. 27, 1993 to Paquet et al., and U.S. Pat. No. 4,770,527 to Park. However, devices which make use of light transmitters and corresponding receivers are not practical for use with live batters who tend to block the light beams. Thus, it is desirable to provide a baseball strike indicator which can be used in a real base-ball game setting and which provides a visual indicator to an umpire when a ball passes through the Strike Zone.